Sliding gate gravity outlets have been used on covered hopper cars for many years. However, it often occurs that these outlets are very difficult to open. Gravity outlets also have caused problems due to leakage of lading, both while the cars are in transit and while they are being unloaded. The AAR has recently proposed a specification which will require that future gravity outlets have improved leakage characteristics and greatly reduced torque requirements to open the gates (not more than 400 foot pounds). It is most preferred that the torque required be even less, not more than about 300 foot pounds.
The methods presently used to lower the opening torque include various types of gear drives. If gearing is used to reduce the required opening torque, the angular shaft rotation required per inch of gate travel is increased throughout the entire travel of the gate an amount equal to the ratio in the gear system.
It is an object of the present invention to provide a gravity outlet in which the force required to open the gate is reduced.
Another object of the present invention is to provide an assembly for reducing the torque required to open the gate which does not increase the angular shaft rotation required throughout the entire gate travel from closed to open position.
Another object of the present invention is to provide a substantially leak-tight closure for the bottom of the hopper.
Other objects will be apparent from the following description and drawings.